Java Oops Concepts Quiz: Test!
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Popularly known as Java's object-oriented programming concepts, Oops form the backbone of java programming. Tech specialists and programmers are familiar with this but giving the quiz a short will be worthwhile in advancing your knowledge.
- 1.The benefits of the Object Orientation are: ( choose two )
- A.
Inheritance
- B.
Flexibility
- C.
Maintainability
- D.
Polymorphism
- 2.Given below the sample code : class Hotel { public int bookings=2; public void book() { bookings++; } } public class SuperHotel extends Hotel { public void book() { bookings--; } public void book(int size) { book(); super.book(); bookings += size; } public static void main(String args[]) { SuperHotel Shotel = new SuperHotel(); Shotel.book(2); System.out.print(Shotel.bookings); } } Find the output of the following code :
- A.
Compile error
- B.
2
- C.
4
- D.
No Output
- 3.HAS-A relationships are based on inheritance, rather than usage.
- A.
True
- B.
False
- 4.Given below the sample code : 1 class Hotel { 2 public int bookings; 3 public void book() { 4 bookings++; 5 } 6 } 7 public class SuperHotel extends Hotel { 8 public void book() { 9 bookings--; 10 } 11 public void book(int size) { 12 book(); 13 super.book(); 14 bookings += size; 15 } 16 public static void main(String args[]) { 17 Hotel hotel = new Hotel(); 18 hotel.book(2); 19 System.out.print(hotel.bookings); 20 }} How can we correct the above code ? (choose all that apply)
- A.
By adding argument "int size" to the method book at line number 3.
- B.
By removing argument '2' at line number 18.
- C.
By creating object of "SuperHotel" subclass at line 17 & calling book(2) from it at line 18
- D.
No correction needed.
- 5.Given below the sample code : import java.io.IOException; class Example7 { public float Twin(float x, float y) throws IOException { return 0; } } class SubExample7 extends Example7 { float Twin(float x, float y) { return 0; } } How can we correct above code ? (choose two)
- A.
No need for correction.
- B.
By changing the method's argument name.
- C.
By removing overridden method 's access specifier(i.e public).
- D.
By adding access specifier 'public' to the overriding method.
- 6.In Java, the actual method executed is determined by the type of the object and not the type of the reference.
- A.
True
- B.
False
- 7.The methods in class object are(choose four)
- A.
Clone
- B.
Notify
- C.
Concat
- D.
Wait
- E.
Equals
- F.
Compare
- 8.Array or collection of superclass references can be used to access a mixture of superclass and subclass objects.
- A.
True
- B.
False
- 9.Given the following sample code: public class Example5{ public float Twin(float a, float b) {... } public float Twin(float a1, float b1) { ...} } How can we correct the above code ?(choose two)
- A.
By placing overriding method into subclass.
- B.
By changing the name of the class.
- C.
By replacing overloading from overriding.
- D.
By changing the name of the arguments.
- 10.A class can inherit instance variables and methods from a more abstract superclass.
- A.
True
- B.
False
- 11.At run-time, a Java program is nothing more than objects ‘talking’ to ___________.
- A.
Other objects
- B.
Other metods
- C.
Other classes
- D.
Other binders
- 12.If you do not have access to the source code for a class, but you want to change the way a method of that class works, then could you use subclassing to do that that is to extend the “bad” class and override the method with your own better code?
- A.
True
- B.
False
- 13.The relation between Car and Owner or BankAccount and Customer is example for
- A.
Aggregation
- B.
Composition
- C.
Association
- D.
None
- 14.Aggregation is a special form of association.
- A.
True
- B.
False
- 15.Subclassing polymorphism is sometimes called “true polymorphism”.
- A.
True
- B.
False
- 16.A method defined in a superclass is redefined in a subclass with an identical method signature is called___________.
- A.
Method overloading
- B.
Method overriding
- C.
Dynamic binding
- D.
Late binding
- 17.Consider the below code and choose the correct output. public class Main { public int a; public long b; public void test(long b) { System.out.println("long b"); } public void test(int a) { System.out.println("int a"); } public static void main(String[] args) { Main e=new Main(); e.test(9*1000000000); } }
- A.
Int a
- B.
Long b
- C.
Long a
- D.
Error
- 18.An interface cannot have an inner class.
- A.
True
- B.
False
- 19.Polymorphism is one interface with __________.
- A.
Single method
- B.
Multiple methods
- C.
Multiple record
- D.
Single record
- 20.Method overloading is done during _______.
- A.
Runtime
- B.
Dynamic binding
- C.
Program compilation
- D.
Late binding
- 21.Interfaces are fast as it requires extra indirection to find corresponding method in the actual class.
- A.
True
- B.
False
- 22.Ad hoc polymorphism is ____________.
- A.
Method Overloading
- B.
Method Overriding
- C.
Subclassing polymorphism
- D.
Dynamic binding
- 23.The inheriting class cannot override the definition of existing methods by providing its own implementation.
- A.
True
- B.
False
- 24.The ability to make changes in your implementation code without breaking the code of others who use your code is a key benefit of _______________.
- A.
Extensibility
- B.
Polymorphism
- C.
Inheritance
- D.
Encapsulation
- 25.Every class in Java is a subclass of class _____________.
- A.
Inheritance
- B.
Object
- C.
Exception
- D.
ArrayList
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